Sans Digital TowerRAID TR4M+ - 4 Bay eSATA RAID 0/1/10/5/JBOD Performance Tower with 6G PCIe Card (Silver) Bundled with RR622 RAID controller card for over 200MB/s RAID 5 performance. Dual-port eSATA 6Gb/s PCIe 2.0 x1 RAID controller supports up to 2 units or 8 hard drives in a single or multiple RAID array. Backward compatible with PCIe 1.0. Supports RAID 0, 1, 10, 5, 5+ spare, spanning and JBOD. Supports online expansion to increase capacity without the need to recreate the RAID volume and erase the existing data. Built-in real time hard drive health monitoring and e-mail notification for critical events. Supports PC, Linux and MAC OS, including Windows 7, Windows Server 2008 and Snow Leopard.